What’s a trick we can use to make sure we do the right thing?

How can you use precommitment to keep yourself from giving in to unwanted desires? You’re probably already doing so—for example, by asking your significant other, on the way to a restaurant, not to let you order dessert when you get there. Dan Ariely, that tireless student of human irrationality, has collected several interesting precommitment anecdotes from regular people, including one who placed her credit card in a container of water in the freezer, thereby requiring a cooling off—er, that is, warming up—period before use, and another who, before a date with a guy she knew she shouldn’t sleep with, wore her “granniest” underwear—presumably to deter herself from disrobing…

Most of us really ought to make more use of such techniques, as Dean Karlan and John Romalis did. The two economists each agreed to lose 38 pounds in six months or forfeit half his annual income to the other. They made a similar deal to keep the weight off afterward. This all worked well enough that Karlan later went on to found stickK.com, a Web site that allows you to provide a credit card number and make a legally binding agreement to do (or not do) a certain thing. If you fail—and you can appoint a referee to decide—then you forfeit the money, which the site will give to a friend or enemy you’ve chosen. (You can also choose a charity you like—or one you hate, such as the George W. Bush or Bill Clinton library, which might be even more motivating.)